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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.awt.dnd;

import java.awt.Point;

import java.util.EventObject;

/**
 * This class is the base class for
 * <code>DragSourceDragEvent</code> and
 * <code>DragSourceDropEvent</code>.
 * <p>
 * <code>DragSourceEvent</code>s are generated whenever the drag enters, moves
 * over, or exits a drop site, when the drop action changes, and when the drag
 * ends. The location for the generated <code>DragSourceEvent</code> specifies
 * the mouse cursor location in screen coordinates at the moment this event
 * occurred.
 * <p>
 * In a multi-screen environment without a virtual device, the cursor location is
 * specified in the coordinate system of the <i>initiator</i>
 * <code>GraphicsConfiguration</code>. The <i>initiator</i>
 * <code>GraphicsConfiguration</code> is the <code>GraphicsConfiguration</code>
 * of the <code>Component</code> on which the drag gesture for the current drag
 * operation was recognized. If the cursor location is outside the bounds of
 * the initiator <code>GraphicsConfiguration</code>, the reported coordinates are
 * clipped to fit within the bounds of that <code>GraphicsConfiguration</code>.
 * <p>
 * In a multi-screen environment with a virtual device, the location is specified
 * in the corresponding virtual coordinate system. If the cursor location is
 * outside the bounds of the virtual device the reported coordinates are
 * clipped to fit within the bounds of the virtual device.
 *
 * @since 1.2
 */

public class DragSourceEvent extends EventObject {

  private static final long serialVersionUID = -763287114604032641L;

  /**
   * The <code>boolean</code> indicating whether the cursor location
   * is specified for this event.
   *
   * @serial
   */
  private final boolean locationSpecified;

  /**
   * The horizontal coordinate for the cursor location at the moment this
   * event occurred if the cursor location is specified for this event;
   * otherwise zero.
   *
   * @serial
   */
  private final int x;

  /**
   * The vertical coordinate for the cursor location at the moment this event
   * occurred if the cursor location is specified for this event;
   * otherwise zero.
   *
   * @serial
   */
  private final int y;

  /**
   * Construct a <code>DragSourceEvent</code>
   * given a specified <code>DragSourceContext</code>.
   * The coordinates for this <code>DragSourceEvent</code>
   * are not specified, so <code>getLocation</code> will return
   * <code>null</code> for this event.
   *
   * @param dsc the <code>DragSourceContext</code>
   * @throws IllegalArgumentException if <code>dsc</code> is <code>null</code>.
   * @see #getLocation
   */

  public DragSourceEvent(DragSourceContext dsc) {
    super(dsc);
    locationSpecified = false;
    this.x = 0;
    this.y = 0;
  }

  /**
   * Construct a <code>DragSourceEvent</code> given a specified
   * <code>DragSourceContext</code>, and coordinates of the cursor
   * location.
   *
   * @param dsc the <code>DragSourceContext</code>
   * @param x the horizontal coordinate for the cursor location
   * @param y the vertical coordinate for the cursor location
   * @throws IllegalArgumentException if <code>dsc</code> is <code>null</code>.
   * @since 1.4
   */
  public DragSourceEvent(DragSourceContext dsc, int x, int y) {
    super(dsc);
    locationSpecified = true;
    this.x = x;
    this.y = y;
  }

  /**
   * This method returns the <code>DragSourceContext</code> that
   * originated the event.
   * <P>
   *
   * @return the <code>DragSourceContext</code> that originated the event
   */

  public DragSourceContext getDragSourceContext() {
    return (DragSourceContext) getSource();
  }

  /**
   * This method returns a <code>Point</code> indicating the cursor
   * location in screen coordinates at the moment this event occurred, or
   * <code>null</code> if the cursor location is not specified for this
   * event.
   *
   * @return the <code>Point</code> indicating the cursor location or <code>null</code> if the
   * cursor location is not specified
   * @since 1.4
   */
  public Point getLocation() {
    if (locationSpecified) {
      return new Point(x, y);
    } else {
      return null;
    }
  }

  /**
   * This method returns the horizontal coordinate of the cursor location in
   * screen coordinates at the moment this event occurred, or zero if the
   * cursor location is not specified for this event.
   *
   * @return an integer indicating the horizontal coordinate of the cursor location or zero if the
   * cursor location is not specified
   * @since 1.4
   */
  public int getX() {
    return x;
  }

  /**
   * This method returns the vertical coordinate of the cursor location in
   * screen coordinates at the moment this event occurred, or zero if the
   * cursor location is not specified for this event.
   *
   * @return an integer indicating the vertical coordinate of the cursor location or zero if the
   * cursor location is not specified
   * @since 1.4
   */
  public int getY() {
    return y;
  }
}
